Abstract: On December 27, 2001, two employees suffered severe thermal burns when the hot water return pipe that they were removing suddenly released 180-degree water. There were four employers involved in this accident: the site employer; the HVAC contractor hired by the site employer to run site employer's HVAC needs; Employee #1, the plumber who was conducting the major plumbing repairs for the site employer; and Employee #2, the backhoe operator, who was contracted by the plumbing contractor to do the digging. Employee #1 was in the process of grinding off the bolts on a flange which connected the 8-inch fiberglass main line to the 4-inch-diameter, 4-foot-high standpipe he was removing. The standpipe was leaking hot water 8 feet underground. The HVAC contractor, who controlled the site, had isolated the segment being worked on by closing the two gate valves at each end of the segment. After some time, sensing that the system had been bled empty, since no water was observed coming out of the drain valve, the HVAC contractor closed the drain valve. Immediately after he closed the drain valve, a six inch strip of the valve seating liner broke and caused water to leak into the isolated, closed pipe. The water, entering the isolated segment at about 70 pounds per square inch, built pressure and caused air and water to release suddenly out of the standpipe which was being removed, some 1,200 feet away. The sudden release of water scalded Employee #1, who was inside the excavation as the water rose approximately 8 to 12 feet into the air for several seconds. Employee #1 was experiencing difficulty exiting the hole because steam had built up inside the excavation. Employee #2, who was watching the plumber, was also burned by the sudden release of hot water because he was sitting on the edge of the excavation and because he assisted Employee #1 up the ladder. Both Employee #1 and Employee #2 were hospitalized for treatment of their burns.